We already know holiday feasting can ruin a diet, but now researchers say weekend gorging is just as detrimental, LiveScience reported.

Over the last 30 years, the obesity rate in America has soared from about 15 percent to about 33 percent in adults aged 20 to 74. In response to these stats, researchers wondered if patterns in people’s eating habits might explain the ballooning figures.

To explore the possible connection, scientists from Quinnipiac University in Connecticut, examined data collected by NPD group, a market research firm serving American food companies. The information detailed the eating habits of 600 individuals who took a national survey in 1998 and 1999.

For two weeks, survey participants tracked foods eaten by household members. Based on those reports, researchers found that people who ate more calories at one meal ate less at the next. They also discovered that, on average, people ate 37 calories more (mostly at breakfast) on the weekends than on weekdays.

The study also showed that people who ate more on the weekends than weekdays for breakfast, lunch and dinner consumed as much as 400 extra calories, a 20-percent increase. In addition, researchers found that during the holidays some study participants devoured 900 additional calories compared with what they ate on other days throughout the year (a 46-percent increase for those individuals).

The big message, researchers said, is that while overeating during the holidays may be bad for your diet so is stuffing yourself on the weekend. Why?

“There’s a lot more weekends than there are holidays,” said study researcher J. Jeffrey Inman, a professor of marketing at the University of Pittsburgh.

Inman suggested people think about the number of total calories they consume. “If you have a big dinner last night, then those calories don’t disappear,” Inman said. “They’re with with you today.”

Uncover other hidden diet mistakes you may be making here.